A phosphor layer is widely used in lamps such as rare gas lamps and fluorescent lamps, and light emitting elements for displays such as PDPs. Among these, rare gas lamps and PDPs are vacuum ultra-violet radiation excited light emitting elements, which are elements that emit light when phosphor layers are irradiated with vacuum ultra-violet rays.
In a PDP, the phosphor layer is produced by applying a phosphor paste on surfaces of a back plate or a baffle by screen printing, direct spraying utilizing a nozzle (dispense method), or the like, followed by drying and baking.
Generally, a PDP has a configuration as described in JP 10(1998)-142781A. Two glass substrates are provided in parallel facing each other, between which interposed are a multiplicity of discharge spaces (hereinafter referred to as “cells”) which are divided by baffles and in which rare gas composed of Ne or Xe as a principal component is capsulated. Among the two glass substrates, one glass plate on the observer side of the PDP is a front plate, and the other glass plate is a back plate. On a back side of the front plate, electrodes are provided, which are covered with a dielectric layer. On the dielectric layer, a protective film (MgO layer) is formed. On a front side of the glass substrate as the back plate, address electrodes are formed so as to cross the electrodes provided on the front plate as described above. Further, a phosphor layer is provided so as to cover a surface of the back plate (corresponding to bottom surfaces of the cells) and surfaces of the baffles. With vacuum ultra-violet rays generated by applying an alternating voltage across electrodes, the phosphor layer is caused to emit light, so that the observer views visible rays that transmit the front plate.
An example of the vacuum ultra-violet radiation excited light emitting element other than the PDP is a rare gas lamp as an illuminating lamp. The rare gas lamp has a configuration similar to the PDP except that the discharge space is not divided by a multiplicity of baffles in many cases. The rare gas lamp attracts attentions from the viewpoint of environment preservation since it does not use mercury, unlike the fluorescent lamp.
The conventional vacuum ultra-violet radiation excited light emitting element such as a PDP or a rare gas lamp does not have a sufficient luminescence, and a vacuum ultra-violet radiation excited light emitting element having a higher luminance and a phosphor layer having a higher luminance for use therein are desired.
An object of the present inventions to provide a phosphor layer having a high luminance and a vacuum ultra-violet radiation excited light emitting element utilizing the same.